For the paired z scores in the following table, compute the value for Pearson's r using the z score formula, and then answer the questions that follow.
[Note that these sets of scores look like z scores, but each set does not actually have a mean of zero and SD of 1.0. Nonetheless, this exercise will give you practice with the z score formula, and the result is realistic.]
zxzy
+1.3+1.4
-2.6+2.9
+0.2-1.6
+1.5+1.9
-2.3-2.3
+0.3+1.5
-3.2+2.8
-1.2-1.7
+2.0+2.0
1. Do these two variables seem to have a strong linear relationship? Draw a graph, and describe what you see.
2. What value did you calculate for Pearson's r? Given the scatter of the points in the graph that you drew for question 1, does the overall Pearson's r for these data come as a surprise to you? Why or why not?